1. Field of the Invention
The present invention relates to a drain pipe of a canister having a canister body in which an adsorbent is accommodated and which is connected to a fuel tank and an intake system of an engine and communicates with the open air.
2. Related Art
A canister adapted to prevent evaporated fuel in fuel tank in an automobile vehicle from being released to the open air includes a drain pipe which permits a lower end of a canister body, having activated carbon as an adsorbent accommodated therein, to communicate with the open air. If the drain pipe is constructed from a single simple pipe, a problem occurs when the opening in the lower end of the drain pipe is blocked due to freezing or icing, clogging with mud or the like, because the exterior air cannot be introduced through the drain pipe when purging the fuel charged to the adsorbent into the intake system of the engine. Therefor, it is a conventional practice to divide the drain pipe at its intermediate portion into an upward pipe portion and a downward pipe portion through two one-way valves, so that even if the opening in the lower end of the downward drain pipe portion is blocked, the open air can be introduced through the opening in the upper end of the upward drain pipe portion.
However, the drain pipe bifurcated and provided with the two one-way valves suffers from a problem that the structure is complicated and comprised of large number of parts, resulting in an increased cost.